GL1zdA wrote:

Some time ago I've realized, that newer graphics cards upscale low resolutions - my monitor reported it got 640x480 when I was playing at 320x240. Does anyone know, when this started? Can I force a GeForce FX to do it? Because I bought a nice NEC 19" LCD display, which works great with all my workstations (they need Sync on Green), but it fails to display anything below 640x480 and I would like to use it with my 98 SE retro PC.

Modern displays may not support 70Hz modes at all, so this might be the reason you don't get the text mode or 320x200 to display correctly.

But even on standard VGA, 320x200 is actually 640x400 mode and 320x240 is actually 640x480 mode but pixels are sent twice and scanlines are sent twice. It started when VGA first came in 1987 😀 So doublescanning is not exactly same as upscaling, at some point graphics cards did upscale everything to native monitor resolution like 1080p.

Okay, on my ASUS V9950 (an GeForce FX 5900) it works on the VGA output but not the DVI output. It also works on the DVI via a DVI to VGA adapter, so it seems it's only the digital part that is causing problems. Indeed, via VGA the display is reporting everything below 640x480 as doublescanned. 320x240 is going to the display as 640x480, 400x300 as 800x600, 512x384 as 1024x768.

Any way to make it work on a pure digital DVI connection?

GL1zdA wrote:

Any way to make it work on a pure digital DVI connection?

My suggestion is to read monitor manual to see if these formats are supported over DVI or not. If it says they are not supported then there is no way.

I don't expect the display to support them, I just would like to know, is there any way to force the GeForce FX to doublescan the resolutions for the digital output.

Similarly, running 320x240 on a GFFX in SVideo will give linear upscaling which looks horrid

GL1zdA wrote:

I don't expect the display to support them, I just would like to know, is there any way to force the GeForce FX to doublescan the resolutions for the digital output.

As far as i know no. Recent Nvidia cards perform what is known as down sampling where you can run a game at a higher resolution than the monitor and it downscales the image to the monitors resolution. I do know that the digital signal processor in many LCD monitors will take a analogue signal and double scale it to meet the lowest available resolution of the monitor. By the way love the avatar gif.

GL1zdA wrote:

I don't expect the display to support them, I just would like to know, is there any way to force the GeForce FX to doublescan the resolutions for the digital output.

The VGA resolutions are already double-scanned on both DVI and VGA interfaces.

My point was, even if the DVI output works just perfectly, if the monitor does not want to support 70Hz signals on DVI interface, then it won't. Many modern monitors refuse to display anything that's 70Hz on DVI/HDMI ports. So this includes VGA 320x200 graphics modes (which is sent to monitor as 640x400 mode at 70Hz), VGA text mode (which is sent to monitor as 720x400 mode at 70Hz), and the EGA 640x350 mode (which has basically same timing parameters as 400-line 70Hz mode).

Jepael wrote:

GL1zdA wrote:

I don't expect the display to support them, I just would like to know, is there any way to force the GeForce FX to doublescan the resolutions for the digital output.

The VGA resolutions are already double-scanned on both DVI and VGA interfaces.

My point was, even if the DVI output works just perfectly, if the monitor does not want to support 70Hz signals on DVI interface, then it won't. Many modern monitors refuse to display anything that's 70Hz on DVI/HDMI ports. So this includes VGA 320x200 graphics modes (which is sent to monitor as 640x400 mode at 70Hz), VGA text mode (which is sent to monitor as 720x400 mode at 70Hz), and the EGA 640x350 mode (which has basically same timing parameters as 400-line 70Hz mode).

I will have to check it with another flat panel. The one that has these problems is a NEC LCD1990SXi which officially works at 70 Hz with some resolutions. Maybe the 320x200 are not doublescanned on DVI?

GL1zdA wrote:

Jepael wrote:

GL1zdA wrote:

I don't expect the display to support them, I just would like to know, is there any way to force the GeForce FX to doublescan the resolutions for the digital output.

The VGA resolutions are already double-scanned on both DVI and VGA interfaces.

My point was, even if the DVI output works just perfectly, if the monitor does not want to support 70Hz signals on DVI interface, then it won't. Many modern monitors refuse to display anything that's 70Hz on DVI/HDMI ports. So this includes VGA 320x200 graphics modes (which is sent to monitor as 640x400 mode at 70Hz), VGA text mode (which is sent to monitor as 720x400 mode at 70Hz), and the EGA 640x350 mode (which has basically same timing parameters as 400-line 70Hz mode).

I will have to check it with another flat panel. The one that has these problems is a NEC LCD1990SXi which officially works at 70 Hz with some resolutions.

So which connectors you are using? The monitor has DVI-D, DVI-I and DSUB15 connectors. Monitor manual says it should support 720x400 @ 70 Hz, which is the timing for VGA text mode, but it does not say anything about 640x400 @ 70Hz. While 720x400 and 640x400 look like identical signals on an analog interface (DVI-I analog or DSUB15) and the monitor will most likely just regard it as 720x400, on digital interfaces (DVI-D or DVI-I digital) the monitor may only accept 720x400 signal, but not 640x400.

GL1zdA wrote:

Maybe the 320x200 are not doublescanned on DVI?

Impossible. Pixel clock would be too low for DVI specification, about one fourth of what the minimum allowed is (25MHz). That's why 320x200 is pixel-doubled and double-scanned to 640x400 to get 25.175 MHz pixel clock, just like it is on analog VGA interface. So most likely, your monitor will show 720x400@70Hz (28.322 MHz pixel clock), but not 640x400@70Hz (25.175 MHz pixel clock) on its digital interfaces.

do you have any idea why dvi (=digital) looks very bad (not sharp, not so good colors) in VGA 320x200 compared to VGA (=analog)
which looks sharp and clear in VGA 320x200? I tested some other tft-monitors (with VGA and DVI) and it seems a generally failure with DVI.
Hires and textmode is fine in DVI.

DVI produces a fine and centered image, but if the lowers is not sharp it's not usefull for my purpose (retro-gaming pc)
It would have been perfect if I could have used DVI for my main gfx-card and use the VGA-IN in the monitor for the voodoo-card.

seems that it's not a good idea.